Search results for "Ordination"
showing 10 items of 1367 documents
Extrinsicvs.intrinsic luminescence and their interplay with spin crossover in 3D Hofmann-type coordination polymers
2020
The research of new multifunctional materials, as those undergoing spin crossover (SCO) and luminescent properties, is extremely important in the development of further optical and electronic switching devices. As a new step towards this ambitious aim, the coupling of SCO and fluorescence is presented here following two main strategies: whether the fluorescent agent is integrated as a part of the main structure of a 3D SCO coordination polymer {FeII(bpan)[MI(CN)2]2} (bpan = bis(4-pyridyl)anthracene, MI = Ag (FebpanAg), Au (FebpanAu)) or is a guest molecule inserted within the cavities of the 3D switchable framework {FeII(bpb)[MI(CN)2]2}·pyrene (bpb = bis(4-pyridyl)butadiyne, MI = Ag (FebpbA…
High oxidation state aqueous organometallics. Formation and structure of an oxo-centred Cp*MoV trinuclear cation by chemical reduction of Cp*2Mo2O5
2002
International audience; Reduction of Cp*2Mo2O5 by zinc/CF3CO2H in MeOH–H2O yields a salt which is composed of [Cp*3Mo3O4(O2CCF3)3]+ and [Zn2(O2CCF3)6]2− ions after crystallisation from THF–Et2O.
Iron(II) Complexes with Scorpiand-Like Macrocyclic Polyamines: Kinetico-Mechanistic Aspects of Complex Formation and Oxidative Dehydrogenation of Coo…
2017
The Fe(II) coordination chemistry of a pyridinophane tren-derived scorpiand type ligand containing a pyridine ring in the pendant arm is explored by potentiometry, X-ray, NMR, and kinetics methods. Equilibrium studies in water show the formation of a stable [FeL]2+ complex that converts to monoprotonated and monohydroxylated species when the pH is changed. A [Fe(H–2L)]2+ complex containing an hexacoordinated dehydrogenated ligand has been isolated, and its crystal structure shows the formation of an imine bond involving the aliphatic nitrogen of the pendant arm. This complex is low spin Fe(II) both in the solid state and in solution, as revealed by the Fe–N bond lengths and by the NMR spect…
Coordination chemistry of N,N′-bis(coordinating group substituted)oxamides: a rational design of nuclearity tailored polynuclear complexes
1999
Abstract The coordinating properties of N , N ′-bis(coordinating group substituted)oxamides have been thoroughly investigated both in aqueous solution and in the solid state. The easy cis – trans isomerization equilibria that they exhibit together with the great variety of N , N ′-substituents which can be used to play on the overall charge, complexing ability and polarity, make them very suitable ligands in designing homo- and heterometallic species. The knowledge of their complex formation in aqueous solution by potentiometry and using the hydrogen ion concentration as a probe, allowed us to settle the basis of a rational design of oxamidate-containing polynuclear species whose nuclearity…
Azacoronands and Azacyclophanes
2012
Azacycloalkanes and azacyclophanes are among the first macrocyclic ligands developed in the field of supramolecular chemistry. Since they are polyamines, they show dual nature in the coordination of both metal cations, when they are in the free-base form, and anionic species, when they are protonated. As a matter of fact, they played a key role in the birth of macrocyclic chemistry of transition metal complexes and anion coordination chemistry. Furthermore, azacyclophanes fostered also the birth of apolar complexation in aqueous solution, since their aromatic units act as binding sites for apolar substrates. Keywords: azacycloalkanes; azacyclophanes; metal complexes; anion complexes; apolar…
Thermodynamic and kinetic studies on the Cu2+ coordination chemistry of a novel binucleating pyridinophane ligandElectronic supplementary information…
2003
The synthesis and coordination chemistry of the novel pyridine-functionalized ligand 2,6,9,12,16-pentaaza[17]-(2,6)pyridinophane (L1) is described. The compound behaves as a hexaprotic base in aqueous solution. NMR studies indicate a protonation pattern in which the sp2 pyridine nitrogen (N(py)) does not undergo a net protonation although it is involved in formation of hydrogen bonds. L1 forms mono and binuclear hydroxylated complexes. The crystal structure of [CuL1](ClO4)2 shows a square planar coordination for Cu2+ with the pyridine and the three central nitrogens of the chain forming the vertices of the square. The benzylic nitrogens could be occupying the axial positions of a strongly a…
Cysteamine and its homoleptic complexes with group 12 metal ions. Differences in the coordination chemistry of ZnII, CdII, and HgII with a small N,S-…
2005
2-Ammoniumethanethiolate, (-)SCH(2)CH(2)NH(3)(+), the first structurally characterized zwitterionic ammoniumthiolate, is the stable form of cysteamine (HL) in the solid state and in aqueous solution. Reactions of ZnCl(2), Cd(Oac)(2), and HgCl(2) with cysteamine and NaOH in a 1:2:2 ratio, respectively, lead to the homoleptic complexes ML(2). Their single-crystal X-ray structures demonstrate basic differences in the coordination chemistry of Zn(II), Cd(II), and Hg(II). While chelating N,S-coordination modes are found for all metal ions, Zn(II) forms a mononuclear complex with a distorted tetrahedral Zn(N(2)S(2)) coordination mode, whereas Hg(II) displays a dimer with Hg(N(2)S(2)) coordinated …
Speciation of tin(II) in aqueous solution: thermodynamic and spectroscopic study of simple and mixed hydroxocarboxylate complexes
2013
This contribution reports the results of potentiometric and Mossbauer investigations on the formation, stability, and structure of binary and ternary mono- and binuclear complexes of Sn2+ with three hydroxocarboxylic ligands (namely L = tartrate, malate, and citrate) and chloride at T = 298.15 K in different ionic media and ionic strengths (0.15 and 1.00 mol dm−3 in NaCl(aq) and 1.00 mol dm−3 in NaNO3(aq)). The stability constants of various simple Sn i H j L (2+−) and mixed Sn i H j L k Cl (2+−−) species obtained in the different experimental conditions are reported, and various speciation diagrams of the simple and mixed systems are shown in different conditions. The sequestering ability …
ChemInform Abstract: Review: Solution Equilibria of Ternary Complexes Formed from Copper(II), Aliphatic Amines, and Bioligands
2014
This review provides a summary of the coordination chemistry of ligands in the ternary system: copper(II)–aliphatic amine–bioligand, where amine = ethylenediamine – En, diethylenetriamine – Dien, or N, N, N′, N″, N″-pentamethyldiethylenetriamine – Me5dien, and bioligand = selected amino acid, aminohydroxamic acid, or aminophosphonic acid, in aqueous solution. We would like to show the specific interactions of copper(II) in ternary systems in the context of complex equilibria chemistry.
ChemInform Abstract: Cryptand-Like Anion Receptors
2010
The design of supramolecular hosts for anions began with simple diaza bicycles, named katapinands, and has evolved over the last 40 years to a number of elegantly designed receptors capable of binding many different anions. About the same time the term cryptand appeared in reference to another bicyclic compound that was selective for alkaline-earth ions. Since the first report these simple bicycles, a vast arena of hosts has appeared, including acyclic, monocyclic, and other multicyclic supramolecular receptors. Studies of these systems have revealed considerable information about anion coordination chemistry, including the fact that many of these complexes mimic their transition-metal coro…